As of build 15882, addons seem very prone to causing crashes. According to Tukz, both the presence of a slash command and the GetRegions() function can cause this, but there are probably more causes.

At the start of beta (when addons were enabled) I also had to remove a couple of global strings I replaced, the more abstract patterns with end of string '$' or something like '|3-7' seemed to cause this. Not sure if this works again, I'd have to test.